Why the meltdown?
If you want to understand why the banks are continuing to implode, and how we got to here, pick up Phillips' book. It's not very technical, yet lays out the situation pretty well.
(If you like politicians - either party, but especially the Republicans - some of it will be hard to take, but hey. And I assume you're not reading it if you're a banker...)
The amazing thing is that the book was published last April, which means he was writing it in 2007, before the end result he writes about actually happened. It reads as if it was written this week.